Such an expansion chuck is mainly intended to firmly clamp a tool, for instance a milling tool or a drill, inside the receptacle. The expansion chuck in turn is mounted on a machine tool at the end opposing the tool receptacle, so the tool can be used to process a work piece.
For clamping a tool in the receptacle, a closed volume formed between the expansion sleeve and the base body is pressurized, e.g., by pressing in oil, causing the expansion sleeve to pressurize inwards in the radial direction, i.e., towards the middle axis of the expansion chuck. This presses the expansion sleeve against the tool inside the receptacle, clamping it inside the receptacle.
To increase the maximum transferable torque between the expansion chuck and the tool, it is in principle desirable that the effective clamping section of the expansion sleeve, that is, the length of the area in which a high compression is generated between the inner surface of the expansion sleeve and the outer surface of the tool when pressurized, be as long as possible. At the same time, the expansion chuck should be as compact as possible in the axial direction. It is therefore desirable to make the clamping section as long as possible without increasing the length of the expansion chuck.
Another requirement for the expansion chuck is to clamp the tool in a manner that avoids any notch effect at the front end of the expansion chuck to the extent possible. Any such notch effect can lead to premature failure of the tool in the long term.